St. Lawrence or St. Vincent
Mausoleum of Galla Placidia, Ravenna, Italy
The bookcase on the left contains the four gospels, labeled by their authors. In the center is a gridiron such as the ones on which the deacon saints St. Lawrence and St. Vincent were martyred. The saint runs in from the left, carrying a long cross and wearing a dalmatic with long vertical stripes such as a deacon would wear.
For a very long time most scholars believed that this was St. Lawrence, whose death by gridiron was being portrayed as early as the 4th century. However, Gillian Mackie has argued that the saint is Vincent. His Passio speaks of his rushing to the gridiron "with quick step. Joy gives him speed." And his punishment is specifically for refusing to lead the authorities to the church's books, which they sought to burn. Further, although he was martyred in Spain Vincent had a widespread following, especially in Ravenna, where he was invoked in the Litany of the Saints and is among the martyrs in the great procession mosaic at Sant'Apollinare Nuovo (Mackie, 54-58).
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Photographed at the site by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.